Field of the Invention
The present invention relates to a feeding apparatus and an image forming apparatus.
Description of the Related Art
An image forming apparatus such as a printer and a copying machine conventionally includes a feeding apparatus for feeding sheets one by one. As a feeding apparatus, a configuration including a stacking plate serving as a sheet stacking unit and a feed roller for feeding sheets on the stacking plate is known.
The feeding apparatus includes a sheet surface detection mechanism for detecting the height of the topmost surface of the sheets on the stacking plate. Japanese Patent Application Laid-Open No. 2011-57386 and Japanese Patent Application Laid-Open No. 2009-202967 discuss configurations in which the sheet surface detection mechanism is arranged in a position downstream of the feed roller.
Japanese Patent No. 4612893 discusses a configuration in which a lifter mechanism for lifting up the stacking plate is mechanically operated based on the height of the topmost surface of the sheets on the stacking plate.
However, Japanese Patent Application Laid-Open No. 2011-57386 and Japanese Patent Application Laid-Open No. 2009-202967 do not discuss a sheet surface detection position in a width direction orthogonal to a feeding direction. Consequently, with the configurations discussed in Japanese Patent Application Laid-Open No. 2011-57386 and Japanese Patent Application Laid-Open No. 2009-202967, it is sometimes been not possible to appropriately detect the sheet surface if the sheets stacked on the stacking plate are curled (wavy) in the width direction. Appropriately controlling the height of the topmost surface of the sheets on the stacking plate is also important in a configuration that mechanically controls the lifter mechanism, like the configuration discussed in Japanese Patent No. 4612893.